Comments on A2 steel

Kodiak PA

Kodiak PA

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What do you guys think of this steel (besides it not being stainless)? Also, does the heat treament determine how stain resistant the steel is?

TIA.I tried searching specifically for A2 but the search engine specifies that you have to have a 3 letter minimum.
 
ive only made 2 from A2, and they cut/tested well, very tough. You can really take the edge down very thin without worries of chipping. I dont have alot of "specific" numbers, but i really liked working with it both in making and in using afterwards.

Ive had 3 customs made with A2. 1 Brend, 1 RJ Martin and 1 Lebetard.

They all shared similar traits, they were all easy to sharpen, they were very responsive to different edge types by using different stones etc...

I actually like it a bit more than D2, seemed a bit less prone to edge chipping under hard use.

Hopefully some of the guys with more experience with A2 than me will reply as well.
 
I have used two A-2 blades, one a Chris Reeves fixed blade and a custom made many years (can't remember the maker), both cut very good and held a excellent edge. IMHO A-2 gets as sharp as any steel i've ever sharpened.
 
As with all relative comments, they depend on your standard of reference. When asked on his forum awhile ago about CPM-3V and the rave reviews it was getting, Kevin McClung commented that if you consider the reference that most makers were using for toughness (ATS-34), it was hardly surprising that they would be very impressed with CPM-3V, not because of its nature specifically, but simply because it was not a high carbon stainless steel. If you compare the toughness of 3V with the traditional "tough" steels like 1084, 5160, etc., it doesn't stand out very strongly at all. It is not even at the top of the field. What are the odds I'd actually reference something McClung said, I think this is a sign that the Rapture is forthcoming.

One of (the most?) most common steels used in high end cutlery now is ATS-34 (154CM). It is a very well known standard and how a lot of people judge the performance of a steel, as ATS-34 has been around for some time, and is similar to other very well known steels like 440C and the varients like VG-10, BG-42, and even tool steels like D2. With D2 actually taking a rise again now, as some people are wanting to move away from stainless into the "tool steel" class. If you view ATS-34 class steels as suitable for heavy work knives, then A2 will be seen as an improvement, and possibly even extreme usage.

There is however another radical perspective. There are large groups of users who consider such alloys to be far to brittle for heavy use knives. Mainly this is because the work that they are doing can damage them. Jerry Busse for example has referenced testing on D2 which shatters the blades, not just breaks them, which is typical for such alloys, the fractures can propogate extensively throughout the bulk of the material in a spiderweb fashion. If this is your perspective then A2 will be seen as a steel that doesn't have the ductility for a heavy use knife, the impact toughness is decent, far better than the ATS-34 blades, but still not nearly as high as the 5160 class materials. This is why there are other steels in the A famility of lower carbon content for more durability such as Johanning uses in his blades.

Will you like the performance of A2 in regards to durability? It depends on what you want from a knife. The kinds of things that will heavily damage ATS-34 blades (induce a significant fracture) are fairly extreme, you are talking about a forceful contact off of a hard object like a rock or hardened metal. Prying being the other big problem as they will break under little flex. Are these concerns? Well it depends on how the blade is being used. For example check the HI and Busse Combat forums for example of field use reports where people comment on such happenings on a semi-regular basis. This is a pretty skewed perspective though as both Bill and Jerry really push people to use their blades, so people tend to be harder on them than most. Temperature also has an effect as ductility and impact toughness will drop as the cold comes in. So someone how works on a regular basis in sub-zero weather will have a different perspective than someone in the tropics.

As a couple of examples, I chipped out a Reeve Project a couple of times doing light chopping when I hit a few nails. The edge broke away, it didn't bend. The same contacts on steels like 5160 tend to just distort the edge to a lesser degree, and it can be aligned. Dent in general are better than cracks as the extent of the damage is more localized and self-contained. You can really induce large dents on steels like 5160 before they propogate and when they do, they rip they don't fracture, and it takes a lot of work to do so. I spent an hour pounding a HI khukuri on small diameter hardwoods with full force hits to get a small dent to rip. The same work would have broken a steel like A2 apart. As another example, I broke the point off of a Mission MPK, prying in wood, it broke under a very low flex. The more ductile steels like 1084, even when fully hardened will be able to take a much greater flex so you have adecent safety margin.

What about edge retention? You can expect better than most of the simpler alloys like 5160 on abrasive materials, and lower performance than the ATS-34 materials. For a lot of materials being cut though, hardness is the primary factor as it determines strength and strength determines resistance to rolling which is the dominant factor in a lot of cases. Thus A2 blades at ~55RC will blunt long before ATS-34 ones at ~60RC on a lot of materials. Toughness can also be a factor depending on what you are cutting, so A2 will be ahead of the ATS-34 class steels and below the 5160 ones.

In short, if you are happy with ATS-34 regarding durability you will be very pleased with A2, if your standards for a heavy work blade are much higher, like one of the simpler carbon alloys, you will find a loss of durability. Edge retention, for low stress cutting will run in much the opposite way. In general most makers who forge blades have a much higher standard for durablity than those who do stock removal, simply because in general, you forge much tougher alloys than you stock remove. So if you ask around makers you will find two very general groups. There are exceptions obviously, there are people who forge CPM-S60V, CPM-10V etc., and those who stock remove 1095, A8, CPM-3V etc..

In regards to heat treatment. Yes it can induce changes in corrosion resistance mainly by changing the extent that the Cr carbides. This is more critical in something like ATS-34 though, as the corrosion resistance of A2 is low no matter how you heat treat it. Low again being relative, it will be better than something like 52100, but not as good as ATS-34 and leagues behind 440A.

-Cliff
 
I wouldn't us A2 to make a machete or a kukri, but for most knife applications it is a very good nonstainless. It actually performs best right at around 60 RC so it holds an edge well when used in cutting applications. It is very fine grained and takes a razor edge easily for an alloy in the 60 RC range. I haven't had corrosion problems with it, but when I sharpen on a wet hone the debris rusts quickly. It works well as a hunting knife since you can slice easily and still have enough toughness to split a pelvis.
 
Cliff, I believe it was you that made some comments about A2 some time ago. Something to the effect of its toughness peaking at 60 HRc. Any higher and it became very brittle, any lower and the toughness went down as well. If these statements were yours, would you care to elaborate? If not, would the person that wrote them care to elaborate?
 
Toughness used in an everyday sense basically means difficult to do. In regards to knives it is also used in much the same manner. I have seen for example knife makers refer to a steel as being tough because it wears belts away quickly during grinding, by this perspective, ceramic is a very tough material. Now it is of course tough to grind, which is what they are saying, but by far what most people mean when they ask if a steel is tough, is in regards to the nature of its ability to resist being broken, ie., "is it tough to break?". Along those lines there are two ways in which you can look at toughness.

The first type of toughness is the resistance to breaking under slow loads. You take a piece of steel and bend it in a vice (or pull it apart) moving past the point where it has taken a set and further until is snaps. The amount of work it took to break the steel defines its toughness. What controls this aspect of performance? Two basic material properties - strength and ductility. Strength gives the material the ability to resist being deformed, and ductility gives the material the ability to take deformation without fracture. The critical point is that both depend in the opposite way on hardness, thus there is a "sweet spot" of sorts in which the hardness will be high enough to give good strength without giving up too much ductility so that it breaks under a very low flex. For example if you temper M2 around 1000F you can get a hardness of 64-67RC. This will be a very strong steel, but not very ductile and thus it will break at a low flex. Thus it is not very tough as while it takes a lot of force to get it to flex, you only have to apply it for a very short period of time as the blade will break very quickly. Thus the total amount of work you have to do is very small.

The second type of toughness is much more direct. You take a piece of steel and hit it with a big hammer and see how much energy it takes to break it. The amount of energy defines the impact toughness and it is usually given in foot pounds (ft.lbs) or Joules (J). The hammer can be impacted off of the steel in a couple of different ways. The steel can also be notched to examine how sensitive it is to a stress risor. The notches can be circular or triangular and steels respond differently to each. For example A2 has a high circular notch (c-notch) impact toughness than O1 but a lesser triangular notch (v-notch) impact toughness. In the same manner as the last type of toughness, the impact toughness also depends both on strength and ductility and thus there is also a "sweet spot". You want enough hardness to give the material the ability to resist deformation, but you can't go too high or else a fracture will be induced which will rapidly spread through the material. For example you can take a file and break it with a sharp rap with a hammer. It is too brittle (because it is too hard) to have a high impact toughness. On the opposite end, if you tested annealed steel, it would just bend too easily under the impact of the hammer as the strength is not high enough.

It is exactly because of this complicated nature of steel that there are "families" of steels of each grade. For example in the A2 class there are steels like A6, A8, A9, which are very similar to A2 but designed for greater toughness (basically they have a lower carbon content). If you harden them to a similar lower RC like ~55 RC, these steels are significantly tougher than the underhardened A2 at the same RC because they are designed for optimal performance at that RC level. This is why in general you should not just underharden (soften) steel to get the necessary toughness but instead look for a related steel which is designed for optimal performance at a higher level of toughness. This also makes life easier on you because those steels will in general be much easier to machine and finish.

You will hear a lot of arguments against this because "its all in the heat treatment". Which I would see as - there are a lot of ways to do it wrong, anyone doing it right should get the same thing. While it is very true that heat treatment effects the properties of steel in a great way and it can't be ignored, it is not that complicated that it can't be done very well with even simple equipment, as an extreme example look at the khukuris from HI. As well consider that the heat treatment of modern steels like A2 is very well known. There is also a tremendous amount of hype about heat treatment. For example deep cryo has never been shown to significantly increase the toughness of steels, even the people who push it the hardest as they sell the equipment (Nu-Bit) make the major claim that it increases wear resistance by altering the carbide formation as opposed to the traditional tempers (which can achieve the other benefits of deep cryo such as grain refinement and increase in martensite transformation). It is possible of course that a maker has found through a lot of experimentation that he can for example induce a better toughness out of A2 at a lower level as opposed to A8 for example, however I don't think it likely given the amount of time spent by so many people to come up with the well known modern standards and it would make the family of steels redundant. Of course if any one has any actual data to contradict this, I would be very interested to see it.

-Cliff
 
WOW, that was a lot of info. Ok here goes the reply. I was interested mostly in toughness as defined by the Charpy v-notch test. Most of the time, when talking about knives, people refer to toughness as the ability to fles w/o taking a set, which is actually the yield strength, or the ability to bend permanently w/o cracking, which is actually ductility. I have a specific definition of toughness and read reviews etc with the difference between mine and most others definitions in mind. A2 has a reputation as being a tough steel, but you info about O1 intrigues me. Where did you get the info. BTW, I have done some impact testing and have found some very interesting results. Several times now I have tested bridge girder material and found that it maxes out our impact machine at 300 ft-lbs. The samples were cooled to 40 degrees F. This isnt really knife related, just interesting stuff. The main reason I asked about the A2 at a reduced hardness is I was wondering about the increased temperature used to reach the lower hardness causing temper embrittlement. Or am I just talking out of my arse and not making any sense?
 
Regarding the lack of evidence to support cryo improving toughness, I read an article a few years ago written by a knife maker that heat treated different blades, some w/ cryo and some w/o. His evidence seemed to support the idea that cryo helped out. On the other hand, the point of his article seemed to be to try to support the marquench, as that was included and his data showed it to be the toughest of the treated blades. His testing was done by an idependant testing lab and they used the Izod toughness test, if I remember correctly. I'll see if I can find it. It was in Knives Illustrated as I recall.
 
Perhaps I misunderstand a lot of comments here about A2 but...
Are you guys saying that A2 is brittle at over 60 and under 60 RC? I thought Criswell's swords were A2 hardened in the upper 50's... Wouldn't that induce catastrophic failure of many of his sword blades based on what you all are saying? I must not be understanding.
 
Sure would be nice if R.J. Martin would chime in here. I would imagine R.J. could provide some useful info about A2.
 
Originally posted by Nobody
Perhaps I misunderstand a lot of comments here about A2 but...
Are you guys saying that A2 is brittle at over 60 and under 60 RC? I thought Criswell's swords were A2 hardened in the upper 50's... Wouldn't that induce catastrophic failure of many of his sword blades based on what you all are saying? I must not be understanding.
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I will try to find the thread that I saw this in....but as I recall, A2 has a toughness 'trough' between 56/57 and 60 RC. Specifically, its toughness is about the same at 57 and at 60, but it is a bit lower between them (weird, huh?). I do not remember much about the toughness of this steel below 57.
 
Nobody,
While it is generally true that as hardness goes up, toughness goes down, it is not carved in stone, and exceptions do exist. As Cliff pointed out in a previous thread, several factors affect toughness, one of which is strength, which is related to hardness. As a quick example, let's compare aluminum to 300 series stainless steel. The aluminum is much softer, but in v-notch impact tests for toughness, the stainless steel will be higher. One of the reasons for this is it is stronger. For the record, I'm not talking about the space age high strength aluminum alloys, which can be stronger than 303 or 304 stainless steel. I am referring to the common ones that aren't heat treatable. This is an extreme case just to illustrate my point. To be fair, I suppose we really should compare steel to steel, not to another alloy entirely.
 
A2 is good steel. Here's some testing done by Gaucho on an A2 Espada I did.

"I bought both a leg of lamb and a big shank of beef for this test, figuring that if Jerry's fighters could cut a leg of lamb, that I would test the Espada out against the toughest flesh and bone I could get( my butcher just glows when he sees me come through the door now, BTW ).

First I hung the leg of lamb and took a #1 angle- forehand diagonal- slash through the thickest part of the shank with the E- cut it through like it wasn't even there! No resistence whatsoever. The D was also able to cut through the leg of lamb successfully, although I did feel the cut more.

Encouraged, I moved right on to the shank of beef. The shank measured 14" long by 12" wide by 9" thick, with a 2" diameter bone running through its length. This thing was heavy- weighing a good 15 Lbs!

Again I took a #1 angle slash through the thickest part of the shank with the E. Cut it clean through! Through 14" by 9" of fascia and muscle, as well as 3" of beef bone on the diagonal! And the cut was just perfect, you guys. The cut piece landed directly below the hanging remainder. That's beyond good. And I have the pictures to prove it(which I will send to you, Jerry, once the film is developed).

OK, so I figured what the hell, and cut a #4- horizontal backhand- and #1 combination- very fast. Splat! The piece fell to the floor right below what little remained hanging. The #4 angle slash had cut all the way through the shank, bone and all, leaving the cut piece hanging from a thread of gristle. The follow up #1 angle slash above it had completely amputated the shank again, dropping it to the floor . That's some serious, serious cutting, my friends, through some very tough flesh and bone.

I rehung a big piece of the shank and cut it with the Dao. It was able to cut through the flesh and part way through the bone consistently, once cutting all the way through the bone, but not out the other side. A good performance, without a doubt, but not even in the same league as the Millennium Espada.

Finally, the E thrust all the way through the shank at will as far up the blade as I wanted with absolutely no resistence.

After all of this, the blade remains perfect- no new scratches, rolled edge, chips, nothing. It is still shaving sharp."

Beef bone is pretty hard. Criswell, Ernie Meyer, R.J. Martin and many other makers have made some very tough blades with it.
 
Nails can damage almost any blade. The top blade in this pic is S30V. The bottom blade is INFI. Both have about the same edge width and bevel. The S30V blade is hollow ground; the INFI is flat. Both hit a 16d nail pounded into a board and bent 45 degrees. The cut was straight down on the bottom inch of the 3-inch nail to minimize flex. The damage was different, but of about the same dimensions. BTW, both blades were easily pounded through the nail when laid flat. I honestly don't think A2 would have faired any worse, but it wasn't a part of this test sequence. BTW, the INFI blade was abused in other ways which is why it looks a little ratty. That's no reflection on the steel. INFI is great steel.

EDIT NOTE: I need to make something very clear here. The INFI blade was modified by me to have the same edge profile I put on the S30V blade. Since I got the INFI blade second-hand, I don't even know what the original edge looked like, so this is definitely not a reflection on the knife or even the steel for that matter. Frankly, if INFI were available to custom makers I would use it in a heartbeat. The point I was making here is that no matter what the steel, it's possible to devise a test that will break it. In this case the INFI didn't break though, it deformed - very different from any carbon steel I've tested. I should also note that human errors occur in this kind of testing, and that can dramatically influence results as well.
 
Elwin :

Where did you get the info.
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Bill Bryson's book on heat treatment of tool steels. I would assume any standard reference would have it.

The main reason I asked about the A2 at a reduced hardness is I was wondering about the increased temperature used to reach the lower hardness causing temper embrittlement.
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The loss of impact toughness sets in before the range at which temper embrittlement sets in, althought it could indeed be a factor at the higher temps.

Elwin, I would appreciate that information. The most extensive testing I have seen done was performed by Nu-Bit who sell cryo equipment. I obviously don't consider them an unbiased source of information since they are testing products they are selling, however I would think that if cryo could be promoted as increasing toughness they would be doing it. There is a huge amount of disinformation about cryo, mainly because there are two large groups arguing about it, the people selling the equipment and those who market the traditional multi-temper approach.

Nobody, brittle is a relative term and thus saying a steel is brittle is meaningless, you have to say it is more or less brittle than something else. A steel will be both brittle and tough depending on what you are comparing it to. For example while it is true that A9 for example has a maximum toughness at ~ 48 RC, even at 56 RC where it is not as tough, it is still much tougher than any stainless steel, and many tool steels. While the c-notch charpy value of A2 does drop off below 60 RC, it would still be above that of ATS-34 for example. Also there are other qualities besides notch toughness, the ductility should increase rather smoothly with a drop in RC hardness.

Without a benchmark for reference Jerry, conclusions are near impossible to draw from the tests you note. As I mentioned before, several low end production blades (AUS-6 etc.) passed very simliar if not identical tests (bone, hardwoods etc.) by the same tester. Thus you can only claim a similar level of durability as the lowest blade to pass the same type of test, which in this case was a low end production AUS-6A. In general, this is how you interpret all durability work.

Now other blades had failed with consistent edge damage or gross blade failure and yours passed, then you would have an arguement for greater durability. For example the damascus blade that suffered a tip bend, you could state that your blades had stronger tips since they didn't bend on similar work. But as noted in the review the tip on the Damascus blade was a little thin and I recall it worked fine when it was reprofiled. Will York found a similar problem with your Bolo, he also damaged the tip, which again could be prevented with more steel in the tip.

Now, if you want to conclude performance was controlled by the steel then you need to be very careful because the blades would need to have geometry that is very similar, with the blades having similar levels of control during the cut, and similar levels of force were used. If the latter are not true steel will not be the defining factor. For example an ATS-34 blade with a 25 degree edge will hold up a lot better under many kinds of impacts than 5160 with a 10 degree edge. This doesn't prove ATS-34 is more durable than 5160.

Interesting testing on the nail, doesn't reflect what I have done however it depends on how the cutting was done though, you will get fractures like that if the cut is partially made and the blade forced to twist out of it and doesn't have the ductility.

In regards to people making "tough" knives. This is a meaningless statement as you are using a relative term without a reference and thus it is undefined. It would be like someone asking me how the wood is around here to cut and I said "easy, its soft". There are Pine, Fir, Birch and Spruce trees around here, different parts of area is more heavily populated with different trees. If I cut in a heavily Spruce area I would have a very different perspective than it I was cutting mostly Pine.

To make my answer meaningful I would simply rank the common wood in this area which would be; Alder (very soft), Pine (soft), Fir (normal), Birch (hard), Oak (harder), Black Spruce (very hard and knotty). This also allows people to answer questions I have in a meaningful answer. If I ask someone how hard Sweetgum is to cut they can give me a definate answer by comparing it to the wood I have used, in this case it is harder than even Spruce (from people I have talked to, I have never cut it).

This is why when asking questions about steel you should give your own viewpoint. For example if the user is pleased with the toughness of D2, he has a very different perspective than someone who needs the toughness of L6. A2 will easily suit one of them, but not the other.

-Cliff
 
Originally posted by Cliff Stamp
Without a benchmark for reference Jerry, conclusions are near impossible to draw from the tests you note. As I mentioned before, several low end production blades (AUS-6 etc.) passed very simliar if not identical tests (bone, hardwoods etc.) by the same tester. Thus you can only claim a similar level of durability as the lowest blade to pass the same type of test, which in this case was a low end production AUS-6A. In general, this is how you interpret all durability work.
-Cliff
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Cliff, you keep repeating this lie and I wish you'd stop. That a knife doesn't ding by NOT making the requisite cut is NOT the same as passing the toughness test while actually making the requisite cut. The test is defined by making the cut, not simply staying in one piece. A butter knife probably wouldn't ding and not pass the test either. Furthermore, nothing Gaucho has tested besides this A2 sword has cut through beef bone, which is much harder and denser than any other bone he has used. If you want to cut lesser materials than beef bone, here were some other results in the same testing.

________________________________________________________________

"First, I clamped a sheet of 1/2" exterior grade plywood to my workbench and executed various slashes and thrusts into it. Here the difference in the blade profiles of the E Vs. the D really stood out. The E. cut cleanly into the plywood from any angle, but only to a depth of 2". Obviously its thicker spine stopped it- as you predicted Jerry. The D typically cut to a depth of 3" - 4".

Thrusting, on the other hand, was a whole different animal. The E actually thrust through the plywood! The tip came all the way through to the other side a good distance. That's amazing! The D couldn't do that to save its life. And absolutely no damage to the E's tip.

And accuracy? Unbelievable! Moving at full speed I can hit within a 1/4" of tiny black spots I dotted on the plywood with a Sharpie. The D is good, believe me- but not this good. The E is as accurate as the much shorter bowie. Remember, this is a 30" long sword we are talking about here!

Next I clamped a 3" dia. length of dry bamboo- very hard, not rotten- to the workbench and slashed at it with diagonal and horizontal cuts. The E cleanly cut through the bamboo at any angle with no tearing of the fibers. The cuts were perfect. The Dao won't cut all the way through this dia. of bamboo without tearing.

Encouraged, I next clamped a 1 1/4" dia. length of solid manau rattan to the workbench and again slashed at it. The E consistently cut 3/4ths of the way through the rattan at any angle with no tearing. The D- despite its thinner edge- cut no better- in fact, its cuts consistently turned up or down into the rattan to follow the line of least resistance. The E cut perfectly straight, on the other hand. The E also cut maple saplings up to 2 1/2" in dia. perfectly.

When I received the Espada, it was easily the sharpest sword, out of the box as it were, that I had ever touched. I was worried, therefore, that such a sharp edge would not be able to withstand cutting hard targets without sustaining serious damage. But, after all this cutting through very dense targets, there were no new scratches, rolled edges, or chips to the E, and it was still shaving sharp.

Next, softer targets- First I cut a thick, two-sided 1/4" cardboard poster/painting packing crate. The E consistently cut 8" to 9" into the crate from any angle, just as good as the thinner bladed D. On a single-layered 1/4" cardboard sheet, I can consistently cut the entire 20" length of the E's sharp edge at any angle, perfectly straight cuts. It slices beautifully, and its blade geometry is terrific.

Next I cleanly cut through a thick cardboard carpet tube. The E transected it at any angle with no tearing. The D can do the same.

Next I filled several large plastic milk and orange juice bottles with water and cut them perfectly through with the E at various angles. The D does this too, but the E definitely cuts them more sweetly. Its cuts were surgical.

Next I cut an empty soda can cleanly with the E- and the base stayed on the table! It was a beautiful thing to see . The D won't cut all the way through a can consistently.

Next, I threw single sheets of paper into the air and cut them as they fell. The E cuts the sheets completely and perfectly straight, time after time. It is a joy to move with. It is fast, without a doubt. The D is not so good at cutting paper cleanly, much less when it is floating."

__________________________________________________________________

As for Will York's testing of the bolo, the point did indeed fail in a manner I had not anticipated. Had I known he was going to pry chunks out of Mesquite, I likely would have profiled the blade differently. Since that was an experimental blade design, I refused to sell or even quote a price on that knife until after Will had completed his testing and concluded the failure was due to unanticipated stresses. Oh yes, that was 154CM, not A2. (and FWIW, I encouraged Will to post those results, after learning the point had failed.)

When making a custom knife, the steel and geometry are selected in combination to provide the necessary capabilities. In fighting bowies, which were for the most part what Gaucho was testing with other blades, it is useless to construct a blade only for strength if using the knife is encumbered by excessive weight. Weight and balance are fundamental considerations of a fighting knife, the need for which is at considerable odds with making the blade as strong as you'd like to ensure it doesn't break. The knife fighter could easily die with a very strong chunk of 1/4" plate in his hand. Prying is not a common tactic in knife fighting, but thrusting into hard objects is. That was understood before the testing was undertaken, and before the knives were designed. Any steel can be made to fail, as the above pix show, but it is necessary to design to the application for each given steel used.

When I edge Ontario Machete's to make them cut more efficiently and endure abuse the standard edge can't tolerate, I do so with the understanding I am working with Rc50 1095 steel. It is not my choice of steel, but it is my obligation to make the most of that steel I can with the geometry I apply to it. Edge geometry is just part of the equation, defined by the application(s) and the steel used. Weight, balance, lateral stresses, environmental stresses, etc., etc. are others.
 
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